The use of intraspecific chemical cues (pheromones) as sex attractants has been reported for the insect order, Trichoptera (the caddisflies) (Wood and Resh 1984). While a number of putative pheromones have been identified, the behavioral efficacy, evolutionary significance, and potential for using these chemicals to assess densities of adult caddisflies remains unknown. The objectives of this project are, first, to field-test putative pheromones that have been identified at the chemical and neurophysiological level, but whose behavioral role is not yet known. If these compounds are indeed pheromones, traps containing the chemicals should attract caddisfly adults. Second, we will explore the use of pheromone traps as a novel technique for water quality assessment. Since caddisfly larvae are found in aquatic habitats, selective sampling of caddisfly adults through the use of pheromones-baited traps may simplify and expedite the identification of species whose presence is indicative of water quality. We will also use histological techniques to explore the organization of olfactory neural pathways in Trichoptera; and compare these with the closely related insect order Lepidoptera (moths and butterflies) in order to gain an evolutionary perspective on form and function of insect olfactory pathways, perhaps shedding some light on the more complex neural pathways found in humans.